Mufflers for marine engines



April 6, 1965 w. M. BETTS ETAL MUFFLERS FOR MARINE ENGINES Filed Nov. 12, 1963 INVENTORJ' vm A BY T zy W United States Patent This invention relates to exhaust mufflers primarily intended for marine engines, said mufilers being of the socalled wet type, an example of which is shown in US. patent to Betts, No. 3,077,240, date February 12, 196 3.

It is an object of the present invention to provide a muffler of this character which will present a relatively large surface area exposed to outside air and without an increase of the overall size of the muifier shell, thereby adding to the cooling effect.

It is an object of the invention to provide a muffler in which the coolant water of the engine is trapped and with which the hot expanding engine exhaust gases mix and are cooled.

It is an object of the invention to provide a muffler having a body or shell of such shape that it greatly resists internal explosions or back-firing and thereby prevents muffler damage often caused thereby.

It is a further object of the invention to provide a mufiler having its baffies formed integrally with the body or shell of the mufiler so that such baflles will not become loosened or detached and blow out as a result of backfire.

It is still another object of the invention to provide a 1;

in axial disalignment, the shell being provided with a a plurality of spaced-apart, circumferential deep grooves resulting in the production of battles extending partly across the interior of the shell, said baffles being composed of distorted portions of the upper and lower shells and having spaced walls defining air spaces between them, this arrangement serving to provide large surfaces exposed to outside air adding materially to the cooling effect that is obtained.

With these and other objects to be hereinafter set forth in view, we have devised the arrangement of parts to be described and more particularly pointed out in the claims appended hereto.

In the accompanying drawing, wherein an illustrative embodiment of the invention is disclosed,

FIG. 1 is a side elevational View of a muffler, constructed in accordance with the invention, with a portion of the exhaust pipe being shown in section;

FIG. 2 is a sectional view, taken substantially on the line 22 of FIG. 1, looking in the direction of the arrows;

FIG. 3 is a sectional view, taken substantially on the line 3--3 of FIG. 2, looking in the direction of the arrows; and

FIG. 4 is a sectional view, taken substantially on the line 4-4 of FIG. 1, looking in the direction of the arrows.

In the embodiment of the invention as illustrated, the shell or body of the muffler is generally indicated at 1, and the same is composed of two parts indicated respectively at 2 and 3. Both of these shell sections may, if desired, be composed of fiberglass or other suitable plastic material, or of metal, and each of these shell sections is generally semi-circular in cross-sectional shape and provided with small radially-extending flanges 4, through which fastening elements 5 may be extended to unite the two sections together or other fastening means can be used, the two sections when secured together forming the hollow muflier shell or body as shown.

The body of the shell 1 can, if desired, be made in one-piece by the so-called blow-mold process of molding and particularly when the shell is composed of polyethyl ene or of a material having similar characteristics, such operation being rapid, and reducing the cost of manufacturing.

In the shell, made as shown described, there is provided at one end an inlet pipe 6, the body or shell being contracted to form said inlet pipe. At the opposite end of the shell is located the outlet pipe 7, the shell being also contracted at that end to form the latter pipe. It will be noted that the inlet and outlet pipes are axially disaligned and this disalignment of the two pipes is an important feature of the present invention.

The lower shell section shown at 3 is provided at spaced intervals with grooves 8, these grooves in this section forming an opening for the gases and Water to pass through, this opening being slightly larger in area than the opening in pipe 7, to eliminate back pressure.

In the opposite or upper section of the shell, or that shown at 2, a plurality of spaced, deep, circumferentiallyextending indentations or grooves 9 is provided, the formation of such grooves 9 resulting in a deformation of the shell section 2 at spaced points to thereby produce a plurality of double-walled bafiles 10 extending into the interior of the shell and across a substantial portion of the depth of the same and to a depth nearly equal to the depth of the shell section 2. The production of these bafiies ill results in the formation of chambers or pockets 11 between them as clearly seen in FIG. 3.

The bafiies 10, produced by the deformation and deep grooving of both shell sections 2 and 3 provides spacedapart opposing walls 12 and 13, resulting in the production of spaces or air grooves 14 between such walls. The result is that a relatively large surface area is provided and as air can pass through the grooves 8 and 9 to contact the wall surfaces 12 and 13, the cooling effect is materially increased.

In order to provide for suitable reinforcement for the inlet and outlet pipes 6 and 7, these pipes may be interiorly reinforced by means of stainless steel inserted perforated sleeves, one of which is shown in the outlet pipe 7 at 15. These sleeves may be provided in both the inlet and exhaust or outlet pipes, and when they are inserted during the molding of the muffler shell, part of the shell sections will exude through the holes in the sleeves as shown at 16, and after curing, or hardening, will lock the sleeves in place. These sleeves provide added reinforcement to the pipes 6 and 7, so that the clamps which are used to hold the mufller in place will be supported.

From the foregoing, the operation of the improved mufiier will be apparent. The hot exhaust gases and water from the engine enter into the muffier as indicated at 20, and the shape of the mufller shell, coupled with the disalignment of the inlet and outlet pipes thereof, traps the coolant water as shown at 21 in the lower section 3 of the shell below the baffles 10. As diagrammatically illustrated in FIG. 3, the hot expanding gases will mix with the coolant Water and the expansion is halted. The cooling of the gases reverses the expansion action and, thus back pressure, which causes loss of power, is lowered. The large surface area that is exposed because of the double-walled bafile formation, aids materially in effecting cooling. The shape of the muffler shell is such as to provide for greater strength to resist damage from possible back-fire, and the absence of separate bafiles provides for a relatively indestructible construction.

Having thus described a single embodiment of the invention, it is obvious that the same is not to be restricted thereto, but is broad enough to cover all structures coming within the scope of the annexed claims.

What we claim is:

1. A mufiler for marine engines comprising, an elongated hollow shell composed of upper and lower sections forming a hollow body, the uppermost of the sections having a plurality of spaced, relatively deep indentations extending across it and transversely to the longitudinal axis of the shell, said indentations forming double-walled bafiles having their walls spaced apart on the outside of said upper section to form air spaces between such walls, and gas expansion chambers between such walls on the inside said baflles extending on the inside of the shell to the center of the upper shell section on which they are formed, the lower shell section having transverse indentations of considerably less depth than those which are formed in the upper section, creating inline openings between the outer ports, whereby Water is trapped in the lower section located below the terminations of the baffies in the upper section.

2. A muffler for marine engines comprising, an elongated hollow shell composed of shell sections joined together on a longitudinal line, the shell having inlet and outlet ports respectively located at its opposite ends, said ports being in axial disalignment, the internal shell sections being provided between the outer ports with a straight passage of greater diameter than the diameter of the ports,

to compensate for the volume of water trapped, one section of the shell being inwardly distorted at spaced intervals to form double-walled baffles for approximately the depth of the shell section on which they are formed, the other section of the shell being indented but with its indentations of less depth than those in the first-mentioned shell section, whereby the battles in the first section form interruptions in said section and those in the second section do not substantially interfere with the continuity of the straight passage through said section.

References Cited by the Examiner UNITED STATES PATENTS 1,426,352 8/22 Brush 181-47 1,815,005 7/31 Hamilton et al 181-62 X 1,821,013 9/31 Hamilton 181-70 X 2,484,827 10/49 Harley 181-49 X 2,859,830 11/58 Holler.

2,877,860 3/59 Hotter. 2,882,072 4/59 Noland 285-239 X 3,077,240 2/63 Betts -Q. 181-61 X 3,080,939 3/63 Kelly 181-52 X 3,095,944 7/63 Buxton 181-57 FOREIGN PATENTS 1,162,405 4/58 France. 287,597 7/31 Italy.

LEO SMILOW, Primary Examiner. 

1. A MUFFLER FOR MARINE ENGINES COMPRISING, AN ELONGATED HOLLOW SHELL COMPOSED OF UPPER AND LOWER SECTIONS FORMING A HOLLOW BODY, THE UPPERMOST OF THE SECTIONS HAVING A PLURALITY OF SPACED, RELATIVELY DEEP INDENTATIONS EXTENDING ACROSS IT AND TRANSVERSELY TO THE LONGITUDINAL AXIS OF THE SHEEL, SAID INDENTATIONS FORMING DOUBLE-WALLED BAFFLES HAVING THEIR WALLS SPACED APART ON THE OUTSIDE OF SAID UPPER SECTION TO FORM AIR SPACES BETWEEN SUCH WALLS, AND GAS EXPANSION CHAMBERS BETWEEN SUCH WALLS ON THE INSIDE SAID BAFFLES EXTENDING ON THE INSIDE OF THE SHELL TO THE CENTER OF THE UPPER SHELL SECTION ON WHICH THEY ARE FORMED, THE LOWER SHELL SECTION HAVING TRANSVERSE INDENTATIONS OF CONSIDERABLY LESS DEPTH THAN THOSE WHICH ARE FORMED IN THE UPPER SECTION, CREATING INLINE OPENINGS BETWEEN THE OUTER PORTS, WHEREBY WATER IS TRAPPED IN THE LOWER SECTION LOCATED BELOW THE TERMINATIONS OF THE BAFFLES IN THE UPPER SECTION. 